Your pitchers are great, i mean even if you lose Darvish you have Kershaw, CJ, Price, wainwright as your top 4. Thats pretty good, i think wainwright will have a great 2nd half.
Losing the closer sux,,personally i like to have 4 closers like you have. I dont think this is a reason to reject though. Especially with the trade deadline coming up there is sure to be some shuffling so id keep an eye on it. Right now id make sure you grab Romo, as it looks like Casilla might be on the way out,,,maybe also frans rodriguez is a good pickup also, just so you have that 4th closer.
the last reason that you should do it is that you have pedroia and phillips at 2nd already. The sox lineup is sick (even sicker with ortiz comes back) Pedroia will have Ellsbury and Crawford hitting infront of him. Not sure it could get better than that. Im a kinsler fan, but making this trade makes sense for your team and kinsler really isnt a big loss/.
Obv your going to need to pick up a couple guys for the ww. Id speculate on a couple closers and a SP. Good luck.